<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8" />
    <title>在线阅读PDF文件</title>
</head>
<body>
<h1>login</h1>
<form action="/user_login" method="POST">
    <p>用户名：</p> <input type="text" name="username"></input>
    <p>密码：</p>  <input type="password" name="password"></input>
    <input type="submit"></input>
</form>
</body>
</html>